JP6347116B2 - Printing apparatus and printing method - Google Patents

Description

  The present invention relates to a printing apparatus and a printing method for performing printing by ejecting ink droplets from ink nozzles.

  In a printing apparatus that performs printing by ejecting ink from an ink nozzle, an ink nozzle that does not eject ink for a certain period of time becomes clogged due to evaporation of moisture from the nozzle tip, increasing the viscosity of the ink. For this reason, ink cannot be normally ejected from ink nozzles with low ejection frequency, and print quality may be deteriorated. Therefore, a maintenance unit is provided in the printing apparatus, and flushing that discharges ink toward the maintenance unit (so-called regular flushing) is performed to prevent or eliminate clogging of the ink nozzles. In addition, flushing that discharges ink onto printing paper (so-called flushing on paper) is performed to prevent or eliminate clogging of ink nozzles.

  Since the regular flushing is performed by moving the print head onto the maintenance unit, a decrease in throughput becomes a problem. In Patent Document 1, in order to suppress an increase in ink consumption and a decrease in throughput caused by performing regular flushing at regular intervals, control is performed so as not to perform regular flushing more than necessary according to the content of printing. Yes. For example, when printing a plurality of the same contents, flushing is not performed on the nozzles used for printing the previous page. In addition, the time during which no ink is ejected is measured for each nozzle, and flushing is performed only for nozzles for which a time equal to or greater than the reference value has elapsed.

JP 11-192729 A

  Thus, there are a plurality of methods for flushing, but each method has advantages and disadvantages. For example, regular flushing does not affect the print quality, but causes a decrease in throughput. Although the decrease in throughput due to the regular flushing can be reduced by the control as in Patent Document 1, it cannot be completely eliminated. On the other hand, flushing on paper can be performed in parallel while performing a printing operation, and therefore does not cause a decrease in throughput. However, since ink is ejected onto the printing paper, it becomes a cause of deterioration in printing quality.

  Here, as a printing mode of the printer, a mode such as a throughput priority mode (so-called fast mode) that prioritizes shortening of the required printing time and an image quality priority mode (so-called clean mode) that prioritizes ensuring print quality is provided. There is. In such a case, the desired flushing method varies depending on the mode. Further, when printing conditions such as printing speed and printing resolution can be set in a plurality of stages, a desirable flushing method varies depending on the printing conditions. Therefore, it is desirable to apply an appropriate flushing method according to the mode and printing conditions.

  In view of such a problem, the present invention performs a combination of flushing for ejecting ink to a maintenance unit and flushing for ejecting ink to a recording medium, so that the balance between throughput and print quality can be achieved. The object is to propose a printing apparatus and a printing method capable of suppressing ejection failure.

  In order to solve the above problems, a printing apparatus according to the present invention includes a print head having ink nozzles, a maintenance unit that receives ink ejected from the ink nozzles, a printing position that performs printing on a recording medium, and A head moving mechanism for moving the print head to a maintenance execution position for discharging ink to a maintenance unit; a first flushing condition for performing flushing by discharging ink to the maintenance unit; and flushing by discharging ink to the recording medium A combination determining unit that determines a combination of conditions for the second flushing to be performed, and a composition for generating composite data in which a pattern of the flushing dots formed by the second flushing based on the determined second flushing condition is added to the image data And the determined first flash And having a first flushing execution unit for executing said first flushing the print head based on the grayed conditions, the.

  Further, the printing method of the present invention includes a combination of the first flushing condition for performing flushing by ejecting ink to the maintenance unit with the ink nozzles of the print head and the second flushing for performing flushing by ejecting ink onto the recording medium. Based on the determined second flushing condition, composite data in which a pattern of flushing dots formed by the second flashing is added to image data is generated, and ink is ejected to the recording medium based on the composite data The first flushing is performed based on the determined first flushing condition.

  The printing apparatus and the printing method of the present invention perform maintenance of the ink nozzles by combining the first flushing for ejecting ink to the maintenance unit and the second flushing for ejecting ink to the recording medium. That is, the first flushing that does not decrease the print quality and the second flushing that does not decrease the throughput can be used in combination, and these can be performed in an appropriate combination. Therefore, it is possible to perform printing while suppressing the ejection failure of the ink nozzles while balancing the print quality and the throughput according to the application and the printing situation.

  The printing apparatus of the present invention has a print mode setting unit that sets one of the first print mode and the second print mode that shortens the time required for printing than the first print mode, The combination determination unit may determine a combination of the first flushing condition and the second flushing condition based on the set printing mode. In the printing method of the present invention, the print mode is set by setting one of the first print mode and the second print mode that shortens the time required for printing compared to the first print mode. Based on the above, it is desirable to determine a combination of the first flushing condition and the second flushing condition. According to the configuration of the present invention, when setting print modes with different priorities, the object can be achieved by appropriately combining the first and second flushing according to the priorities. For example, in the mode giving priority to print quality (second print mode), the first flushing that does not lower the print quality is mainly performed, and in the mode giving priority to throughput (first print mode: mode for shortening the time required for printing). It is desirable to mainly perform the second flushing that does not reduce the throughput. According to the configuration of the present invention, it is possible to perform printing while suppressing the ejection failure of the ink nozzles while balancing the print quality and the throughput according to the print mode.

  In the printing apparatus of the present invention, the printing apparatus includes an image quality setting unit that sets a print resolution, and the combination determination unit determines a combination of the first flushing condition and the second flushing condition based on the set print resolution. It is desirable to decide. When the generation period of flushing dots is the same, the density of flushing dots due to flushing on paper varies depending on the printing resolution. This means that the influence of the second flushing on the print quality is different. Therefore, by combining the first and second flushing in consideration of the print resolution, it is possible to perform printing while suppressing the ejection failure of the ink nozzles while balancing the print quality and the throughput.

  In the printing apparatus according to the aspect of the invention, it is preferable that the frequency of performing the first flushing is determined as one of a first frequency and a second frequency that is less frequently than the first frequency. When the frequency of the first flushing is high, the degree of recovery of the ink nozzles by the first flushing is large. Therefore, by combining the first and second flushing in consideration of the frequency of the first flushing, it is possible to perform printing while suppressing the ejection failure of the ink nozzles while balancing the print quality and the throughput.

  In the printing apparatus according to the aspect of the invention, it is preferable that the density of the flushing dots in the second flushing is determined to be either a first density or a second density less than the first density. In the second flushing, when the density of flushing dots is high, the degree of recovery of the ink nozzles by the second flushing is large. Therefore, by combining the first and second flushing in consideration of the density of flushing dots, it is possible to perform printing while suppressing defective ink ejection while balancing the print quality and throughput.

  In the printing method of the present invention, as the first flushing condition, the strength of the first flushing is determined to be either the first strength or the second strength with a smaller ink discharge amount than the first strength. Is desirable. When the strength of the first flushing is large (that is, the amount of ejected ink is large), the degree of recovery of the ink nozzles by the first flushing is large. Therefore, by combining the first and second flushing in consideration of the strength of the first flushing, it is possible to perform printing while suppressing the ejection failure of the ink nozzles while balancing the print quality and the throughput.

FIG. 2 is a schematic block diagram illustrating a control system of a printer to which the present invention is applied. FIG. 2 is an explanatory diagram schematically illustrating a print head, a maintenance unit, and a print sheet of the printer of FIG. 1. It is explanatory drawing which shows the conversion process from image data to printing data. It is explanatory drawing of a combination table. It is explanatory drawing which shows a flushing pattern typically. It is explanatory drawing of the combination table of another form. It is a graph which shows the correspondence of printing speed and flushing dot density.

  Hereinafter, embodiments of a printing apparatus and a printing method to which the present invention is applied will be described with reference to the drawings. In the following embodiments, the present invention is applied to an ink jet printer. However, the present invention is also applicable to a printing apparatus having functions such as a scanner and a facsimile. In addition, although the following embodiment includes a line head type print head, the present invention is also applicable to a printing apparatus including a serial head type print head.

(printer)
FIG. 1 is a schematic block diagram showing a control system of a printer to which the present invention is applied, and FIG. 2 is an explanatory diagram schematically showing a print head, a maintenance unit, and printing paper of the printer of FIG. As shown in FIGS. 1 and 2, the printer 1 prints with a print head 2 that ejects ink droplets of four colors of cyan ink C, magenta ink M, yellow ink Y, and black ink Bk, and the print head 2. A transport mechanism 3 that transports the printing paper P (recording medium) along a transport path that passes through a position where the printing is performed, and a head movement that moves the print head 2 in a direction that intersects the transport direction of the printing paper P by the transport mechanism 3. Receives the mechanism 4, the maintenance unit 5, the control unit 6 that controls the print head 2, the transport mechanism 3, the head moving mechanism 4, the maintenance unit 5, and the like, input data (image data) to be printed, print setting information, and the like. Communication unit 7 and the like.

  The print head 2 is a line-type inkjet head, and includes four sets of inkjet heads 2C, 2M, 2Y, and 2Bk arranged at a predetermined interval along the conveyance direction A of the printing paper P as shown in FIG. . Each of the inkjet heads 2C, 2M, 2Y, and 2Bk performs printing by ejecting ink onto the printing paper P because the length in the paper width direction B intersecting the transport direction A is longer than the maximum width of the printing paper P. The inkjet head 2Bk disposed at the uppermost stream in the transport direction A of the printing paper P ejects black ink Bk, and the inkjet head 2C on the downstream side ejects cyan ink C. The inkjet head 2M disposed on the downstream side of the inkjet head 2C ejects magenta ink M, and the inkjet head 2Y on the downstream side ejects yellow ink Y.

  The ink jet heads 2C, 2M, 2Y, and 2Bk include four head units 21 to 24 arranged in the paper width direction B. The four head units 21 to 24 are arranged so that adjacent head units move back and forth in the transport direction A. The four head units 21 to 24 include two ink nozzle rows in which a plurality of ink nozzles 25 are arranged at a predetermined nozzle pitch in the paper width direction B. The nozzle pitch is set to 300 dpi, for example. The two ink nozzle rows are arranged by shifting the position in the paper width direction B by a dimension that is ½ of the distance between the adjacent nozzles (nozzle pitch). Further, the head units 21 and 22 adjacent in the paper width direction B are arranged so that the ink nozzles 25 at the end portions overlap when viewed in the transport direction A. Similarly, the head units 22 and 23 and the head units 23 and 24 adjacent in the paper width direction B are also arranged so that the ink nozzles 25 at the end portions overlap when viewed in the transport direction A.

  The maintenance unit 5 is disposed outside the conveyance path in the width direction. The print head 2 is moved by the head moving mechanism 4 to a printing position C facing the printing paper P on the transport path and a retreat position D facing the maintenance unit 5. In the standby state in which printing is not performed, the nozzle surface of the print head 2 is capped by the maintenance unit 5. In addition, the print head 2 is moved to the retracted position D facing the maintenance unit 5 at a predetermined timing before starting printing or during printing standby, and the ink is ejected from the ink nozzle 25 toward the maintenance unit 5 at regular intervals. Perform flushing.

  In this embodiment, as will be described later, flushing that discharges ink droplets from the ink nozzles 25 located at a position facing the printing paper P (so-called flushing on paper) is performed during printing. In the regular flushing, flushing is performed on all the ink nozzles 25 including the ink nozzles 25 that are not used at the time of printing, for example, the ink nozzles 25 located outside the paper width direction B of the printing paper P. Accordingly, flushing can be performed on the ink nozzles 25 located at positions away from the printing paper P, and the clogging can be prevented or eliminated.

(Control system)
As shown in FIG. 1, the control system of the printer 1 includes a control unit 6 including a CPU and the like. A communication unit 7 is connected to the input side of the control unit 6. The control unit 6 is supplied with input data 10 (see FIG. 3) to be printed and print setting information such as a print mode from an external device such as a computer via the communication unit 7. On the other hand, the print head 2, the transport mechanism 3, the head moving mechanism 4, the maintenance unit 5 and the like are connected to the output side of the control unit 6. The transport mechanism 3 includes mechanisms such as a paper feed roller pair that transports the printing paper P, a transport motor that is rotated by a control signal from the control unit 6, and a driving force transmission mechanism that transmits the rotation of the transport motor to the paper feed roller pair. . The head moving mechanism 4 is based on a carriage on which the print head 2 is mounted, a carriage guide shaft that supports the carriage so as to be movable in the paper width direction B, a carriage motor that is rotated by a control signal from the control unit 6, and rotation of the carriage motor. A pulley that rotates and a mechanism such as a timing belt that is stretched around the pulley.

  The control unit 6 includes a storage unit 61, a rendering unit 62, a color conversion processing unit 63, a binarization processing unit 64, a print mode setting unit 65, a combination determination unit 66, a flushing dot composition unit 67 (composition unit), and print data generation. Unit 68, print control unit 69, periodic flushing execution unit 70 (first flushing execution unit), and the like. The control unit 6 also includes a conveyance control unit (not shown) that conveys the printing paper P at a designated speed by controlling the conveyance mechanism 3.

  The storage unit 61 stores a color conversion lookup table 71, an SML table 72, a combination table 73, a flushing pattern 74 (74A, 74B), and the like.

(Conversion process from input data to print data)
FIG. 3 is an explanatory diagram showing a conversion process from input data to print data. The rendering unit 62 performs a rendering process for converting the input data 10 (image data or the like) to be printed into image data 11 having the number of pixels corresponding to the designated print size and resolution. Specifically, the input data 10 is enlarged or reduced to a designated print size, and decomposed into pixels so as to have a designated resolution. The pixels of the image data 11 after the rendering processing are RGB color system color data (RGB multivalued data).

  The color conversion processing unit 63 refers to the pixel (RGB multi-valued data) of the image data 11 after the rendering process with reference to the color conversion lookup table 71 and the ink amount data 12 of four colors C, Y, M, and Bk. Color conversion processing for conversion to (12Bk, 12C, 12M, 12Y) is performed. In the color conversion look-up table 71, ink amount data of four colors C, Y, M, and Bk is stored for RGB multi-value data (a combination of R, G, and B) that is color data of the RGB color system. It is associated. The ink amount data of C, Y, M, and Bk is represented by, for example, an 8-bit gradation value (256 gradations).

  The binarization processing unit 64 converts the pixel ink amount data into the four-gradation dot data that can be formed by the ink nozzles 25 for the ink amount data 12 (12Bk, 12C, 12M, 12Y) after the color conversion processing. Perform the process. In the SML table 72, the gradation values of the ink amount data of C, M, Y, and Bk are associated with the occurrence rates of four types of dots including blank dots. The four types of dots are Null (blank dots), S (small dots), M (medium dots), and L (large dots). First, the binarization processing unit 64 refers to the SML table 72 and performs a dot ratio determination process for converting the ink amount data of the pixel into the occurrence rate data of four types of dots. Halftone processing is performed to determine the presence / absence of each dot size. As a result, a print dot pattern 13 (13Bk, 13C, 13M, 13Y) in which any one of four types of print dots including a blank dot is designated with respect to the pixel position for each ink color is generated. Note that BRS correction for correcting the ink amount based on the arrangement error of the ink nozzles 25 and the ink ejection error may be performed before the ink amount data 12 after the color conversion process is converted into dot data.

  The print mode setting unit 65 sets the print mode based on the print setting information supplied to the control unit 6. In the present embodiment, two types of print quality priority mode (first print mode) and required print time priority mode (second print mode) can be set as print modes. The print quality priority mode is a mode for ensuring print quality. Further, the required print time priority mode is a mode in which the required print time is shorter than the print quality priority mode.

  Based on the set print mode, the combination determination unit 66 performs the regular flushing (first flushing) for ejecting ink to the maintenance unit 5 and the on-paper flushing (second flushing) for ejecting ink to the printing paper P. Determine the combination. A combination of regular flushing and on-paper flushing performed when the input data 10 is printed is determined with reference to the combination table 73.

FIG. 4 is an explanatory diagram of the combination table 73. As shown in this figure, in the combination table 73, the combination of the execution contents of the regular flushing and the execution contents of the on-paper flushing is associated with the print mode. The implementation content of the regular flushing is set by, for example, the implementation frequency and implementation intensity of the regular flushing. The execution frequency is an execution interval of regular flushing, and in this embodiment, two stages of a first frequency (for example, an interval of 10 to 20 s) and a second frequency less than the first frequency (for example, an interval of 1200 s) are provided. . The second frequency is set to be equal to or longer than the required printing time for one roll paper, and when the roll paper is used as the printing paper P, the periodic flushing is not required in the middle of the roll paper. The actual strength is the ink discharge amount, and in this embodiment, there are provided two levels of the first strength and the second strength that has a smaller ink discharge amount than the first strength. On the other hand, the content of the flushing on paper is set by the density of ink dots (hereinafter referred to as flushing dots) formed by flushing on paper. In this embodiment, the first density (for example, 1000 dots / inch ² ) and the first density are set. Two stages of less second density (eg, 200 dots / inch ² ) are provided.

  As shown in FIG. 4, in the combination table 73, with respect to the print quality priority mode, the execution frequency of periodic flushing is set to the first frequency (high frequency), and the execution intensity of periodic flushing is set to the second intensity (low ink discharge amount). ) And a combination in which the flushing dot density of the flushing on paper is the second density (low density) is determined. Also, with respect to the print duration priority mode, the periodic flushing execution frequency is set to the second frequency (low frequency), the periodic flushing execution intensity is set to the first intensity (large ink discharge amount), and the flushing dot density of the flushing on paper is set to A combination of the first density (high density) is determined. In this way, the combination of periodic flushing and flushing on paper increases the flushing dot density of flushing on paper when the frequency of regular flushing is low, and lowers the flushing dot density of flushing on paper when frequency of regular flushing is high. Is set. The intensity of the regular flushing is set so as to increase (increase) the ink discharge amount when the regular flushing is infrequent.

  The flushing dot composition unit 67 adds the flushing dots to the print dot pattern 13 (13Bk, 13C, 13M, 13Y) after the halftone process, and generates the composite dot pattern 14 (14Bk, 14C, 14M, 14Y). The addition of the flushing dots is performed using the flushing pattern 74 (see FIG. 5). Here, the flushing pattern 74 is a pattern for designating the ink nozzles 25 that eject ink droplets and the timing thereof when performing on-paper flushing that ejects ink droplets onto the printing paper P when the input data 10 is printed. In this embodiment, the storage unit 61 stores two flushing patterns 74 (74A and 74B) having different flushing dot densities. That is, the flushing pattern 74A is a pattern in which the density of flushing dots is the first density (high density). The flushing pattern 74B is a pattern in which the density of flushing dots is the second density (low density).

  The flushing dot composition unit 67 selects one of the flushing patterns 74A and 74B in accordance with the on-paper flushing content determined by the combination determination unit 66. That is, referring to the combination table 73, in the print quality priority mode, the flushing pattern 74A in which the density of flushing dots is the second density (low density) is selected. In the time required for printing time priority mode, the flushing pattern 74B having the first density (high density) of flushing dots is selected.

  FIG. 5 is an explanatory view schematically showing the flushing pattern 74 (74A, 74B). FIG. 5A is a first density (high density) flushing pattern 74B, and FIG. 5B is a second density (low). Density) flushing pattern 74A. As shown in this figure, the flushing pattern 74 (74A, 74B) is a dot matrix pattern composed of blank dots and flushing dots Df. FIG. 5 shows an example of a dot matrix pattern of 10 columns × 10 rows and 10 columns × 25 rows for the sake of simplicity, but a dot matrix pattern having a different number of rows and columns is used. You can also. The column direction V of the flushing pattern 74 (74A, 74B) corresponds to the arrangement direction of the ink nozzles 25 (that is, the paper width direction B). The row direction H of the flushing pattern 74 (74A, 74B) corresponds to the flushing execution timing. The size in the row direction H of the flushing pattern 74 (74A, 74B) is obtained by replacing the flushing execution cycle (that is, the flushing dot Df generation cycle) with the number of dots. The flushing pattern 74 (74A, 74B) is a one-cycle flushing pattern. The flushing execution timing is designated by the position of the flushing dot Df in each row.

  When adding the flushing dot Df to the print dot pattern 13 (13Bk, 13C, 13M, 13Y), for example, the print dot pattern 13 (13Bk, 13C, 13M, 13Y) and the flushing pattern 74 (74A / 74B) are overlapped. Thus, the printing dot at the position where the flushing dot Df is superimposed and the flushing dot Df are combined. At this time, if the flushing pattern 74 (74A / 74B) is smaller than the print dot pattern 13 (13Bk, 13C, 13M, 13Y), the flushing pattern 74 (74A / 74B) is repeated in the row direction H and the column direction V. What is necessary is just to superimpose the arranged pattern. The flushing pattern 74 (74A / 74B) is superimposed on the four printed dot patterns 13 (13Bk, 13C, 13M, and 13Y) while shifting the offset amount for each color determined by the ink color. The print dot and flushing dot Df combining process is a process in which the larger dot size is set to the dot size after combining. For example, when the dot size of the flushing dot Df is M, when the flushing dot Df is combined with a print dot having a size equal to or smaller than M, the combined dot size is M. When the flushing dot Df is combined with the L size printing dot, the combined dot size is L. In this way, the synthesized dot pattern 14 (14Bk, 14C, 14M, 14Y) is generated by synthesizing the flushing dot Df.

  The print data generation unit 68 assigns each dot of the composite dot pattern 14 (14Bk, 14C, 14M, 14Y) to the ink nozzles 25 of the inkjet heads 2C, 2M, 2Y, 2Bk, and is used for driving the print head 2. A print data generation process for generating the print data 15 is performed. Here, the ink nozzles 25 overlap in the transport direction A at the end portions of the four head units 21 to 24 as described above. For this reason, in the print data generation process, a mask process for assigning dots to one of the two overlapping ink nozzles 25 is performed. Further, in this mask process, when the dots assigned to the ink nozzles 25 overlapping in the transport direction A are the dots obtained by combining the flushing dots Df and the printing dots, the dots are assigned to both the overlapping ink nozzles 25.

  The print control unit 69 controls ink ejection from the print head 2 based on the generated print data 15. That is, the print control unit 69 generates a pulse of a voltage applied to the piezoelectric element corresponding to the ink nozzle 25 as a drive signal based on the print data 15 and supplies it to the print head 2. As a result, the print head 2 is driven, and ink droplets are ejected from the ink nozzles 25 of the inkjet heads 2C, 2M, 2Y, and 2Bk, and the contents designated by the input data 10 and the print setting information are printed.

  When the periodic flushing execution unit 70 prints the input data 10 by ejecting ink from the ink nozzles 25 based on the generated print data 15, the regular flushing execution content (execution strength) determined by the combination determination unit 66. In addition, regular flushing for discharging ink from the ink nozzles 25 toward the maintenance unit 5 is performed in accordance with the frequency of execution). That is, the regular flushing execution unit 70 drives the head moving mechanism 4 according to the set execution frequency, and moves the print head 2 to the retracted position D facing the maintenance unit 5. Then, the print head 2 is driven to eject ink to the maintenance unit 5 and regular flushing is performed.

(Printing method)
With the above configuration, the printer 1 performs printing according to the following flow. When the control unit 6 of the printer 1 receives the input data 10 such as image data and the print setting information via the communication unit 7, the rendering processing, color conversion processing, and binarization processing (described above) for the input data 10 ( Dot ratio determination processing and halftone processing). On the other hand, the print mode is set based on the print setting information, and referring to the combination table 73, the periodic flushing for ejecting ink to the maintenance unit 5 and the on-paper flushing for ejecting ink to the printing paper P are performed. Determine the combination. Then, in accordance with the content of the on-paper flushing in the determined combination, a synthesis process for adding the flushing dot Df to the print dot pattern 13 (13Bk, 13C, 13M, 13Y) generated from the input data 10 is performed to obtain the synthesized dot pattern. 14 (14Bk, 14C, 14M, 14Y) is generated based on the print data 15.

  In addition, the control unit 6 drives the transport mechanism 3 to transport the print paper P toward the print head 2, and performs a cueing operation for positioning the leading portion of the print area of the print paper P at the print position by the print head 2. Do. When the cueing operation is completed, a drive signal is supplied to the print head 2 based on the print data 15. As a result, the print head 2 is driven, ink droplets are ejected from the ink nozzles 25 of the inkjet heads 2C, 2M, 2Y, and 2Bk, and printing of the contents designated by the input data 10 and the print setting information is performed. The controller 6 performs an operation of driving the print head 2 based on the print data 15 to eject ink onto the printing paper P, and an operation of driving the transport mechanism 3 to transport the printing paper P. Further, the head moving mechanism 4 is driven at a frequency determined in the determined contents of the regular flushing, and the print head 2 is moved to the retracted position D facing the maintenance unit 5. Then, the print head 2 is driven to eject ink to the maintenance unit 5 and regular flushing is performed.

  Since the flushing dot Df is added to the print data 15, an ink dot (print dot) that forms a pixel of the input data 10 by driving the print head 2 according to the print data 15 and ejecting ink onto the print paper P. And the operation of forming ink dots (flushing dots) for performing flushing of the ink nozzles 25 are performed. That is, printing of an image or the like on the printing paper P and flushing on paper are performed.

  As described above, in the printer 1 of the present embodiment, when the input data 10 is printed, the regular flushing for discharging ink from the ink nozzles 25 of the print head 2 to the maintenance unit 5 based on the print setting information such as the print mode, and the printing A combination determination process for determining a combination of flushing on paper for ejecting ink onto the paper P is performed. Then, based on the determined combination, the flushing dot Df formed by flushing on paper is added to the input data 10 to be printed (specifically, the print dot pattern 13 obtained by converting the pixels of the image data 11 after rendering into ink dots). Thus, the composite dot pattern 14 is generated. Thereafter, a printing process for ejecting ink onto the printing paper P based on the composite dot pattern 14 is performed, and when the printing process is performed, a regular flushing is performed based on the determined combination. In this way, according to the printing mode, by appropriately combining regular flushing that does not reduce print quality and on-paper flushing that does not reduce throughput, the balance between print quality and throughput can be achieved according to the application and printing conditions. Printing can be performed and ejection failure of the ink nozzles 25 can be prevented.

  Specifically, in the present embodiment, two types of print modes are provided: a print quality priority mode and a required print time priority mode. In the print quality priority mode, the frequency of regular flushing that does not deteriorate the print quality is increased, and the density of flushing on paper is decreased. Further, in the required print time priority mode that prioritizes throughput, the density of on-paper flushing that does not reduce throughput is increased, and the frequency of regular flushing is decreased. Thus, printing can be performed while balancing print quality and throughput according to priority.

(Other forms)
In the above embodiment, the combination of the contents of regular flushing and on-paper flushing is determined according to the print mode, but the combination is determined according to print setting information other than the print mode (for example, print speed, print resolution, etc.). You can also

  FIG. 6 is an explanatory diagram of a combination table in another form. In this form, the printing speed can be set in two stages, and either high speed printing (300 mm / s) or low speed printing (150 mm / s) can be selected in the print setting. In this case, the control unit 6 includes a speed setting unit, and sets the printing speed based on the printing speed setting information supplied to the control unit 6. In the combination table 173 of this embodiment, the execution contents of the regular flushing and the execution contents of the on-paper flushing are associated with the printing speed. Specifically, for high-speed printing, the same combination as the above-described required time for printing priority mode (that is, the periodic flushing execution frequency is set to the second frequency (low frequency) and the periodic flushing execution intensity is set to the first intensity (ink). The combination of the flushing dot density of the flushing on paper as the first density (high density)) is associated. For low-speed printing, the same combination as the above-described print quality priority mode (that is, the periodic flushing frequency is set to the first frequency (high frequency), and the regular flushing strength is set to the second strength (low ink discharge amount)). And the flushing dot density of the flushing on paper is a second density (low density)).

  FIG. 7 is a graph showing the correspondence between the printing speed and the flushing dot density. As shown in this graph, the density of flushing dots is increased or decreased in inverse proportion to the printing speed. However, since the printing resolution (that is, the printing dot density) is inversely proportional to the printing speed (paper feed speed), a common flushing pattern used for adding the flushing dots Df can be used.

  In this embodiment, based on the print speed setting information, the combination table 173 is referred to determine the combination of the contents of regular flushing and on-paper flushing. As a result, in high-speed printing, it is possible to perform printing by increasing the density of on-paper flushing that does not reduce the throughput and decreasing the frequency of regular flushing. In low-speed printing, the frequency of regular flushing that does not deteriorate the print quality is increased to reduce the density of flushing on paper. As a result, printing can be performed while balancing print quality and throughput in accordance with the user's print speed setting.

  Further, the combination of the implementation contents of the regular flushing and the on-paper flushing may be determined according to the printing resolution (image quality) instead of the printing speed. That is, the print resolution (image quality) can be set in two stages, and in the print setting, either a high image quality with a high print resolution or a low image quality with a low print resolution can be selected. In this case, the control unit 6 includes an image quality setting unit, and sets the print resolution based on the image quality setting information supplied to the control unit 6. Then, as shown in FIG. 6, high-speed printing is replaced with low image quality, and low-speed printing is replaced with high image quality. As a result, printing can be performed while balancing print quality and throughput in accordance with the user's image quality setting.

  For printers that can independently adjust the print mode, print speed, and print resolution, create a combination table that sets the implementation details of regular flushing and on-paper flushing for these print setting combinations. It is also possible to appropriately adjust the implementation ratio of the regular flushing and the on-paper flushing.

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Print head, 2C, 2M, 2Y, 2Bk ... Inkjet head, 3 ... Conveyance mechanism, 4 ... Head movement mechanism, 5 ... Maintenance unit, 6 ... Control part, 7 ... Communication part, 10 ... Input data , 11: Image data, 12: Ink amount data, 13: Print dot pattern, 14: Composite dot pattern, 15: Print data, 21-24: Head unit, 25: Ink nozzle, 61: Storage unit, 62: Rendering unit 63 ... Color conversion processing unit, 64 ... Binarization processing unit, 65 ... Print mode setting unit, 66 ... Combination determination unit, 67 ... Flushing dot synthesis unit (synthesis unit), 68 ... Print data generation unit, 69 ... Printing Control unit 70... Regular flushing execution unit (first flushing execution unit) 71 71 Color conversion lookup table 72 72 SML table 73 Matching table, 74, 74A, 74B ... Flushing pattern, 173 ... Combination table, A ... Conveying direction, B ... Paper width direction, C ... Printing position, D ... Retraction position (first flushing execution position), Df ... Flushing dot, H: Row direction, V: Column direction, P: Printing paper (recording medium)

Claims (8)

A print head having ink nozzles;
A maintenance unit for receiving ink ejected from the ink nozzles;
A head moving mechanism for moving the print head to a printing position for printing on a recording medium, and a maintenance execution position for discharging ink to the maintenance unit;
A combination determination unit for determining a combination of a first flushing condition for performing flushing by ejecting ink to the maintenance unit and a second flushing condition for performing flushing by ejecting ink to the recording medium;
A combining unit that generates combined data in which a pattern of flushing dots formed by the second flushing based on the determined second flushing condition is added to image data;
A first flushing execution unit for causing the print head to execute the first flushing based on the determined first flushing condition;
I have a,
It said first flashing condition of the combination determining section is set by the execution frequency and implementation strength, condition of the second flushing printing apparatus according to claim Rukoto set by the density of the flushing dots. A print mode setting unit that sets one of the first print mode and the second print mode that shortens the time required for printing compared to the first print mode;
The printing apparatus according to claim 1, wherein the combination determination unit determines a combination of the first flushing condition and the second flushing condition based on the set printing mode. It has an image quality setting section that sets the print resolution,
The printing apparatus according to claim 1, wherein the combination determination unit determines a combination of the first flushing condition and the second flushing condition based on the set print resolution. The combination determining unit, as a condition of the first flushing, claim 1 to determine the said frequency of performing first flushing, and a first frequency, to either the second frequency frequency than the first frequency is less 4. The printing apparatus according to any one of items 3 to 3. Claim wherein the combination determining section, for determining a condition of the second flushing, the density of the flushing dots of the second flushing, and a first density, to either the second density less than the first density The printing apparatus according to any one of 1 to 4. A combination of a first flushing condition for performing flushing by ejecting ink to a maintenance unit with an ink nozzle of a print head and a second flushing for performing flushing by ejecting ink to a recording medium;
Based on the determined condition of the second flushing, generate composite data in which a pattern of flushing dots formed by the second flushing is added to image data,
Ink is ejected to the recording medium based on the composite data,
There line the first flushing based on the determined first flushing condition,
The first flushing condition is set according to an execution frequency and an execution intensity, and the second flushing condition is set according to the density of the flushing dots . Setting any one of the first print mode and the second print mode for shortening the time required for printing compared to the first print mode;
The printing method according to claim 6, wherein a combination of the first flushing condition and the second flushing condition is determined based on a set printing mode. 8. The condition according to claim 6, wherein the execution intensity of the first flushing is determined as one of a first intensity and a second intensity with a smaller ink discharge amount than the first intensity. Printing method.

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